I'm a relative beginner myself having only gotten a 5R back in November.

That said, I feel compelled to say that apart from lenses, any beginner should consider getting some good software like Adobe Lightroom. I myself only just started using it but I've already been astounded by how much I've been able to save and enhance pictures from the RAW file. I kind of scoffed at the price at first but after having used it and considering how much more people are willing to shell out for a single lense, the cost seems insignificant considering what it can do for your pictures.